I went reading PB Help and found I could make a deployment as opposed to a development build style only from the command line interface.
There was some entendre about superuser stuff with mention of root, so I did sudo pbxbuild install to gain a successful build where, when I hadn't, I got permissions denied and failed build.
But, the deployment didn't go where I had put it in projectbuilder, so I couldn't click on it to see whether it would see the plugins.
The apps used to work from a click in the build folder, so I think this working hypothesis that deployment was all that important for our level was overly optimistic and that hacking away at how to deploy just might be sour grapes anyway.
I am siezing on another hopeful working hypothesis in my lateral thinking, that the solution to your problem might also solve my problem of actually making plugins plural.
When I simply drag files with .plugin into Application Support plugins aren't seen as having a principle class, somehow, unless I am running from the project that generated them. I checked this with my version of plugin app and Mikes.
So, this is just an idea, a step along the way, not the answer. I try to remember that victory only comes to the frustrated.